The FDA's Category 2 list restricted 19 peptides from compounding. Now, approximately 14 of them may be coming back. HHS has signaled that peptides previously barred from compounding spanning categories like Dihexa: A Comprehensive Guide to This Promising Peptide Dihexa (also known as PNB 0408) is an experimental small molecule derived from angiotensin IV. It was engineered to cross the bloodbrain barrier and has shown synaptogenic effects in preclinical models. The often quoted Important Update on FDA Changes Concerning Peptides DIHEXA Research Capsules Peptide Tech